Save the exact code, status, related codes and freeze frame before clearing. Do not order a sensor automatically: assess the symptoms, inspect the connector and wiring, then use information matched to the exact engine, model year and VIN.
What P0340 reports — and what it does not prove
The controller uses camshaft position to synchronise fuel injection and, depending on the engine, ignition and variable valve timing. P0340 means the expected bank 1 sensor A circuit signal is missing or cannot be used under the monitored conditions.
The word ‘circuit’ matters. Power, ground, signal wiring, connectors, the mechanical target, installation, clearance and software strategy can all be involved. P0016 instead describes an implausible crankshaft-to-camshaft correlation.
P0340 alone is not sufficient evidence to replace the camshaft position sensor.
Hard starting, stalling or rough running: assess urgency
Some vehicles show only a steady warning light; others may crank longer, idle roughly, stall, lose power or fail to start, depending on the fallback strategy. Record whether it happens hot, cold, after repair or intermittently.
Stop safely if the engine stalls in traffic, will not start, makes unusual mechanical noise, or a red oil-pressure or temperature warning appears. Reading a code is never a reason to keep driving through severe symptoms.
- Capture P0340, its status and every related code.
- Save available freeze-frame data before clearing.
- Record hot/cold start, weather, recent work and vibration.
- Do not handle connectors near moving or hot parts with the engine running.
Useful checks before buying a part
With the engine stopped and cold, look for an unlocked connector, contamination, or wiring that is rubbed, pinched or stretched after previous work. Circuit measurements require the wiring diagram and specifications for that vehicle; there is no universal pinout or voltage to apply blindly.
If P0340 returns after a sensor replacement, stop replacing parts. Have the harness, connectors, sensor target and installation checked, then mechanical timing where symptoms support it, and finally VIN-specific bulletins and calibrations.
- Sensor connector condition and locking.
- Harness rubbing, pinching, repairs or heat exposure.
- Power, ground and signal using manufacturer data.
- Sensor clearance, target and installation for the engine.
- VIN-applicable bulletin, calibration or previous repair.
Five manufacturer situations that rule out automatic diagnosis
These documents show three genuine cause families: electrical connection, physical sensor clearance and software logic. They give no failure rate and cannot be transferred to an unlisted European vehicle.
| Vehicle | Engine / year | Official observation | Evidence and limit |
|---|---|---|---|
| Listed Cadillac, Chevrolet and GMC full-size SUVs/pick-ups | 4.3 LV3, 5.3 L83 or 6.2 L86; 2014–2019 by model | When standard diagnosis does not isolate intermittent P0340/P0341, GM directs inspection for corrosion at connector X154 or X159 for the stated year. | PIP5335C; strong manufacturer evidence, exact North-American models and years only. |
| Subaru Legacy / Outback | 2.5; 2013 model year | Out-of-specification camshaft-position sensor clearance can contribute to P0340, hard starting, rough idle or no start. | 11-130-13; manufacturer bulletin, FA/FB applications and professional procedure only. |
| Subaru Impreza / XV Crosstrek | Impreza 2.0 2012–2013; XV 2013 | Subaru calls for waveform analysis and clearance measurement before deciding on correction; the code alone does not condemn the sensor. | 11-130-13; listed applications and production VIN references, North America. |
| Subaru Forester / BRZ | Forester naturally aspirated 2011–2014; BRZ 2013 | The same bulletin includes P0340 among cam-position or misfire codes that may relate to incorrect sensor clearance. | 11-130-13; do not extrapolate to turbo engines or other years. |
| Chrysler Pacifica RU | 3.6 V6; 2017 | FCA changed P0340 from a one-trip to a two-trip fault and specifies a PCM update within the bulletin’s application. | 18-002-19 Rev. A; P0340 logic stated for NAFTA, exact engine, transmission and eligibility required. |
These are manufacturer cases, not OBDPhone® tests of the listed powertrains. They establish neither a failure rate, specific compatibility nor a universal repair.
A decision order that avoids guesswork
Document the fault and symptoms first. Inspect what is visible, then test the circuit with vehicle-specific data. If the electrical signal is sound, a professional may need to check the target, clearance, installation, mechanical timing and software for that engine.
After a confirmed repair, clear P0340 and re-read after the specified operating conditions. A temporarily extinguished light is not proof that the cause has gone.
Useful order: save, assess symptoms, inspect, measure to the diagram, verify VIN, repair, then confirm.
What OBDPhone® can do with P0340 — and its limits
On a compatible vehicle, OBDPhone® can read P0340 and other generic engine and emissions codes, show engine data exposed by the vehicle and save a report. Clear only after repair or a justified check.
OBDPhone® does not directly measure the sensor waveform or prove mechanical timing. It does not guarantee manufacturer functions, relearns, coding, programming, ABS, airbags or traction-battery access. Use a professional for electrical measurements, oscilloscope testing or VIN procedures. Support: support@obdphone.com.
Frequently asked questions
The essential answers.
Does P0340 mean the camshaft sensor has failed?+
No. The sensor is one possibility; connector, wiring, target, clearance, installation or calibration may also be involved.
Can I drive with P0340?+
It depends on symptoms and the manual. A steady light without symptoms needs prompt checking; stalling, no start, unusual noise or a red warning requires more caution.
What is the difference between P0340 and P0016?+
P0340 concerns the bank 1 camshaft-position sensor A circuit. P0016 concerns crankshaft-to-camshaft position correlation.
Can OBDPhone® confirm a failed sensor?+
No. It reads generic engine/emissions codes and available data. Confirmation requires the correct vehicle-specific measurements.
This guide supports an initial understanding. It does not replace the vehicle manual, manufacturer safety instructions or an assessment by a qualified professional.
Primary sources
Reviewed to verify the facts and show why procedures depend on the vehicle.